1. Volume 22, Issue 6, Pages 796-811 (December 2012)
JAK2/STAT5 Inhibition Circumvents Resistance to PI3K/mTOR Blockade: A Rationale for Cotargeting These Pathways in Metastatic Breast Cancer 
Adrian Britschgi, Rita Andraos, Heike Brinkhaus, Ina Klebba, Vincent Romanet, Urs Müller, Masato Murakami, Thomas Radimerski, Mohamed Bentires-Alj 
Cancer Cell 
Volume 22, Issue 6, Pages (December 2012)
DOI: /j.ccr
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2. Figure 1 Dual PI3K/mTOR Inhibition by BEZ235 Activates JAK2/STAT5
(A) Immunoblots of lysates from breast cancer cells grown as monolayer cultures or as xenografts and treated with BEZ235 (BEZ). Mice bearing xenografts were treated with vehicle (VHC) or 30 mg/kg BEZ and dissected as indicated. The numbers indicate the ratios of pSTAT5/STAT5 as measured by densitometry. pJAK2 levels were measured in triplicate by ELISA and normalized to total JAK2 levels (y axis). ERK2 levels were used as a loading control.
(B) Immunoblots of lysates from breast cancer cells in which JAK2 and/or JAK1 were depleted by siRNA (siJAK). siNT, nontargeting control siRNA.
(C) Immunoblots of lysates from 8 hr BEZ-treated MDA468 cells in which JAK2/STAT5 signaling was blocked by JAK2 siRNA (left panel) or by the JAK2-specific inhibitor NVP-BSK805 (BSK) (right panel). ELISA data are means ± SD (n = 3).
See also Figure S1.
Cancer Cell  , DOI: ( /j.ccr )
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3. Figure 2 Cotargeting PI3K/mTOR and JAK2 Reduces Cell Viability
(A) Immunoblots of lysates of breast cancer cells after 20 hr of treatment with BEZ or BSK alone or in combination. DMSO, lysates of cells treated with 0.005% DMSO for 20 hr.
(B) Bar graphs showing the mean percentage of cell viability measured by the WST-1 assay (upper left) and by Trypan Blue cell counts (upper middle) of cell lines grown under 0.5% serum and treated with 300 nM BEZ and/or 350 nM BSK for 72 hr. Bar graph representing colony formation frequencies of cells treated as indicated (upper right). Immunoblots of lysates from the same cell lines after 8 hr of treatment as indicated are shown in the lower panel. Data are means ± SEM (n = 4, ∗p < 0.05).
(C) Bar graphs showing the mean percentage of apoptotic and dead cells after 48 hr of treatment as measured by FACS analysis of AnnexinV and PI stained cells treated with 300 nM BEZ and/or 350 nM BSK as indicated (left panel). Immunoblots of lysates from cells treated with 300 nM BEZ and/or 350 nM BSK for 24 hr (right panel). Data are means ± SEM (n = 5, ∗p < 0.05).
See also Figure S2.
Cancer Cell  , DOI: ( /j.ccr )
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4. Figure 3
Dual PI3K/mTOR Inhibition Induces IL-8 Secretion in BEZ235-Insensitive Breast Cancer Cells
(A) Immunoblots of lysates from cells treated for 1 hr with conditioned media from cells treated with 300 nM BEZ for 20 hr. Lysates of cells treated with medium containing BEZ (SN BEZ ctrl) were used as a control for the BEZ present in the conditioned media. ELISA data are means ± SD (n = 3).
(B) Cytokine arrays showing expression of the indicated cytokines in supernatants of cells treated with 300 nM BEZ for 24 hr (upper panel) or in tumors from mice treated with 30 mg/kg BEZ for 10 days (lower panel). Mouse MIP2 is the functional homolog of human IL-8.
(C) Bar graphs showing the levels of IL-8 secretion (left panel) and mRNA (right panel) in cells treated with 300 nM BEZ as indicated. Levels of IL-8 were measured by ELISA and RT-qPCR and are shown as means ± SEM (n = 4, ∗p < 0.05).
(D) Scatter plot showing correlation in breast cancer lines between IL-8 secretion and the ratios of pJAK2/JAK2 upon BEZ treatment for 20 hr and 8 hr, respectively. Grey: luminal-like lines. Black: TNBC lines. Values from BEZ-treated relative to DMSO cells are shown (see also Table S1). Data are means of three independent experiments (n = 16, correlation = 0.77, p = ).
(E) Scatter plots showing breast cancer lines as in (D), depicted based on the ratios of pJAK2/JAK2 (left panel), the levels of secreted IL-8 (right panel) upon BEZ treatment, and sensitivity toward BEZ. The horizontal lines represent mean values (n = 3, ∗p < 0.05).
(F) Bar graphs showing the mean percentages of cell viability as measured by the WST-1 assay of two BEZ-insensitive lines (left panel) and two BEZ-sensitive lines (right panel) grown under 0.5% serum and treated with 300 nM BEZ and/or 350 nM BSK for 72 hr. Data are means ± SEM (n = 4, ∗p < 0.05).
See also Figure S3 and Table S1.
Cancer Cell  , DOI: ( /j.ccr )
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5. Figure 4
Cotargeting PI3K/mTOR Induces Biphasic Activation of JAK2/STAT5
(A) Immunoblots of lysates from cells treated with DMSO or 300 nM BEZ alone or in combination with IgG or a CXCR1-blocking antibody added 1 hr before lysis. The numbers indicate the ratios of pSTAT5/STAT5 as measured by densitometry. ELISA data are means ± SD (n = 3).
(B) Immunoblots of lysates from cells treated with 300 nM of BEZ as indicated.
(C) Immunoprecipitation (IP) and immunoblotting of lysates from cells treated with DMSO or 300 nM BEZ for 8 hr. WCL, whole cell lysates.
(D) Immunoblots of lysates from cells in which IRS1 was depleted by siRNA before treatment with DMSO or 300 nM BEZ for 8 hr. ELISA data are means ± SD (n = 3) (upper panel). Bar graphs showing the levels of IL-8 secretion upon treatment with 300 nM BEZ for 20 hr (lower panel). Levels of IL-8 were measured by ELISA and are shown as means ± SEM (n = 4, ∗p < 0.05).
(E) Bar graphs showing the levels of IL-8 secretion (left panel) and mRNA (right panel) upon treatment with 300 nM BEZ for 20 hr (left panel) or 8 hr (right panel). Levels of IL-8 were measured by ELISA and RT-qPCR, and are shown as means ± SEM (n = 4, ∗p < 0.05). For immunoblots of lysates from siSTAT5 depleted cells see Figure S2B.
(F) Bar graphs showing the levels of IL-8 secretion (left panel) and mRNA (right panel) upon treatment with 300 nM BEZ and/or 350 nM BSK for 20 hr (left panel) or 8 hr (right panel). Levels of IL-8 were measured by ELISA and RT-qPCR, and are shown as means ± SEM (n = 4, ∗p < 0.05).
See also Figure S4.
Cancer Cell  , DOI: ( /j.ccr )
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6. Figure 5
Cotargeting PI3K/mTOR and JAK2/STAT5 Reduces Primary Tumor Growth, Tumor Seeding, and Metastasis
(A–D) Growth curves of tumors and immunoblots of tumor lysates from mice treated with VHC, 30 mg/kg BEZ, 120 mg/kg BSK, or 25 mg/kg BEZ and 100 mg/kg BSK. In (C) JAK2 was depleted in tumors by doxycycline (dox) administration to induce expression of a JAK2-targeting shRNA (shJAK2). shNT, nontargeting shRNA. Injection refers to orthotopic cell injection and the arrows indicate initiation of treatment and/or administration of dox. Immunoblotting was performed on tumors harvested after 14 days of treatment for MDA468, 10 days of treatment for MDA231 LM2, and 6 days of treatment for 4T-1. Results are mean tumor volume ± SEM (three independent experiments, total n = 4–8, ∗p < 0.05, ∗∗p < 0.01).
(E) Bar graphs showing the circulating tumor cell (CTC) index. The number of CTCs was measured by FACS analysis of GFP+ cells in tail vein blood performed 21 days (MDA231 LM2) or 5 days (4T-1) after initiation of the treatment as in (B)–(D). The CTC index was calculated by dividing the total number of GFP+ CTCs per 100 μl peripheral blood by tumor volume. Data represent the means ± SEM (for MDA231 LM2 shJAK2 in two independent experiments, total of n = 4 mice, and for the other models in three independent experiments, with a total n = 7 mice; ∗p < 0.05).
(F) Drawings of the experimental setup.
(G) Representative IHC pictures of lungs from VHC-, BEZ-, BSK- and BEZ/BSK-treated animals. Left panel: H&E- (left) and Vimentin-(right) stained lungs from MDA231 LM2-bearing animals, treated as described in (B) and (F). Scale bar represents 250 μm. Right panel: H&E-stained lungs from 4T-1-bearing animals, treated as described in (D) and (F). Arrows indicate metastases; the images to the right are magnifications of single metastatic foci. Scale bar represents 200 μm.
(H) Bar graphs showing the metastatic index of mice treated as in (B–D) calculated by dividing the total number of visible lung metastases nodules by tumor volume. Data are means ± SEM (for MDA231 LM2 shJAK2 from two independent experiments, total n = 4, for the other models from three independent experiments, total n = 10, ∗p < 0.05).
See also Figure S5.
Cancer Cell  , DOI: ( /j.ccr )
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7. Figure 6
PI3K/mTOR Inhibition Increases, whereas JAK2 Inhibition Blocks IL-8 Secretion and Reduces the Tumor-Initiating CXCR1+ Subpopulation
(A) Bar graphs showing IL-8 levels measured by ELISA (left and middle panels) or quantification of dots of cytokine arrays (right panel) from tumors of mice treated as in Figures 5A–5D. Data are means ± SEM (n = 3–8, ∗p < 0.05).
(B) Bar graphs showing IL-8 levels measured by ELISA in plasma of mice bearing tumors treated as in Figures 5A–5C. Data are means ± SEM (n = 4, ∗p < 0.05).
(C) Bar graphs showing relative invasion of MDA231 LM2 cells seeded on Matrigel-coated Boyden chambers and treated with 300 nM BEZ, 350 nM BSK and/or CXCR1 blocking antibody. Invasion was assessed after 48 hr. Data represent relative invasion values normalized to cell number and are means ± SEM (n = 4, ∗p < 0.05).
(D) Growth curves of tumors from mice treated with VHC, 30 mg/kg BEZ, 120 mg/kg BSK, 20 mg/kg Repertaxin (Rep), or 25 mg/kg BEZ, 100 mg/kg BSK and 20 mg/kg Rep. Injection refers to orthotopic cell injection and the arrow indicates initiation of treatment. Data are mean tumor volume ± SEM (n = 4–8, ∗p < 0.05).
(E) Bar graphs showing CTC (upper panel) and lung metastatic (lower panel) indices of mice treated as in Figure 5F. Rep was administered at 20 mg/kg. Data are means ± SEM (n = 3–4, ∗p < 0.05).
(F) Upper: representative images of FACS dot plots of CXCR1-stained tumors, CTCs and lungs. Lower: bar graphs showing the percentage of CXCR1+ cells. Data are means ± SEM (n = 6).
(G) Bar graph showing percentages of CXCR1+ cells in MDA231 LM2 tumors of mice treated as in Figure 5B. Data are means ± SEM (n = 4–6, ∗p < 0.05).
(H) Representative dot plot of FACS analyses performed on CXCR1- (upper panel), AnnexinV-, and PI-stained (lower panel) MDA231 LM2 cells treated with inhibitors as in Figure 2C. Bar graphs show the mean percentages of apoptotic and dead cells after 48 hr of treatment. Data are means ± SEM (n = 4, ∗p < 0.05).
(I) Upper: drawing of the experimental setup. Mice bearing MDA231 LM2 tumors were treated as in Figure 5B. The tumors were dissected, dissociated, and retransplanted at different dilutions. Cell viability prior to retransplantation was analyzed by PI-FACS staining and was found to be equal in all treatment groups (data not shown). Lower: bar graph showing the TIC frequencies after treatment as in Figure 5B. Data are mean estimates from three independent experiments, total n = 7 mice, ∗p < 0.05, ∗∗∗p <
See also Figure S6.
Cancer Cell  , DOI: ( /j.ccr )
Copyright © 2012 Elsevier Inc. Terms and Conditions

8. Figure 7
BEZ235 Treatment Activates JAK2/STAT5 and IL-8 Secretion in Primary Human TNBC Xenografts
(A) Immunoblots of lysates from primary TNBC xenografts treated for 4 days with 30 mg/kg BEZ or VHC. ELISA data are means ± SD (n = 3).
(B) Bar graphs showing IL-8 levels measured by ELISA in the dissected tumors from or in the plasma of mice at day 3 of treatment with 30 mg/kg BEZ or VHC. Data are means ± SEM (n = 3–4, ∗p < 0.05).
Cancer Cell  , DOI: ( /j.ccr )
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9. Figure 8
Cotargeting PI3K/mTOR and JAK2 Increases Event-Free and Overall Survival in Two Models of Metastatic Breast Cancer
(A) Upper: drawing of the experimental setup. Lower: Kaplan-Meier survival curves of MDA231 LM2 (left) and 4T-1 (right) tumor-bearing mice treated with BEZ and/or BSK as in Figures 5B and 5D. An event was scored when a tumor reached 1 cm3 (n = 4, ∗p < 0.05, ∗∗p < 0.01).
(B) Upper: drawing of the experimental setup. Lower: Kaplan-Meier survival curves of MDA231 LM2 (left) and 4T-1 (right) tumor-bearing mice treated with BEZ and/or BSK as in Figures 5B and 5D. An event was scored when a mouse showed any sign of distress; (n = 4, ∗p < 0.05, ∗∗p < 0.01).
(C) Schematics illustrating the identified positive feedback loop triggered by inhibition of PI3K/mTOR and offset by JAK2/STAT5 inhibition. Upper: effects of PI3K/mTOR inhibition and/or JAK2 inhibition at the cellular level. Lower: effects of PI3K/mTOR and/or JAK2 inhibition at the tumor level.
Cancer Cell  , DOI: ( /j.ccr )
Copyright © 2012 Elsevier Inc. Terms and Conditions